Rotatable joint for coaxial cables



22, 1950 c. L. ROUAULT 2,519,933

ROTATABLE JOINT FOR COAXIAL CABLES Filed Sept. 2, 1944 Irv/enter: Charles L. Rouault,

b 6 AWL/424 Patented Aug. 22, 1950 ROTATABLE J OINII FOR COAXIALLCABLES 1 Charles" L Renault, Schenectady, N; -Y. assignor 1 to General Electric -Companxwazcorporation of New stern-1:

Application -Septemben2, 1944, .Serialjhlo.,552,392'

3 Cia imss (Cl. 174-21=)-.-

My invention relates to a transmission line for highvfrequency: currentsandlit has for its object to provide a new and improved rotatable joint for a transmission.linesof the concentric conductor type.

In ultra *high frequency signalling apparatus,

and in particular, apparatus which employs a rotatable antennaior either-directing .or receiving signals, it is desirable .to transmit, without reflection, signals between theantenna andhigh frequency. apparatus connected (therewith; It. is known in such systems to use. amcoaxialgtransmission Jinewhichprovides shielded transmission of-ihighl frequency currentauand -in many in-'1 stanceszwhere higher voltages are, employed,.suchi transmissionlines are filled with n-gaseous. me:

diumitoaprevent discharge betweenlthe COIldllC-L tors. ath'ereoi.

It is an object of the present invention to provide a new andr'improved :rotatablek joint for a concentric transmission .line. of the gas-filledv ype The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing, in which the single figure is a longitudinal view, partly in section, showing a portion of a concentric transmission line employing the rotatable joint of my invention.

Referring to the drawing, I have shown two adjacent sections of a concentric transmission line comprising, respectively, tubular outer conductors I, 2 and centrally disposed inner conductors 3, 4. The inner conductors are shown as hollow tubes, although solid conductive rods may be employed instead. The inner conductors are maintained in a central position within the outer conductors by means of a plurality of insulators 5. The outer conductor l at its righthand end, is provided with a spherical end member 6 and the outer conductor 2, at its lefthand end, is provided with a similar spherical end member which fits over the end member 6 and comprises a hemispherical portion 1 attached to the conductor 2 and a zone-shaped portion 8 which slips over the spherical member 6. The portions 1 and 8 are provided with opposed flanges 9, I and are clamped together by means of a plurality of bolt and nut combinations II. The zone-shaped portion 8, at its left-hand end,

is provided with a shoulder portionlZ machined" to fit the outer-surface of-the' spherioatmember 6 to obtain good conductive-connectiontherewith.

A contact' ringdfi is' attached to-the inner -surface-ofthchemispherical portion has by weldingpr brazingyandprovides a-=conductive :con-' nection betweenthe "part1 and the.-member 6.- Interposed' between I the contact rings 12, I3 is a packing materiall lg-illustrated as of the chev--' ron 'type, -fo'r-preventing-leakage of gas from the transmission lines A rotatableconductive connection between the inner cond-uctorsofthe members 3,4 of the trans-:- mission line is provided and comprises a spheri-' *cal member lfi having'a threaded stud l6 fo'r attachment to the conductorfiyand a hemispherical ,contact'imember 1 'l' conductively connectedto the innerrconductorfl 'by-"means' of a tubular plug i a "which extends within the-conductor 4 and is fastened thereto --by-means--of-=a pin-l9. The, tubular plug -|8-is "adapted-t0 fitwithinasleeve pottion m attached to the hemispherical contact'mem'ber- IT. spring 2! located within the tubular plug I8 engages a base portion 22 of the plug, maintaining the member I! in contact with the spherical member l5. When the rotatable joint is used in a gasfilled transmission line, the insulators 5 may have a plurality of longitudinal holes 23 to permit free communication of gas between the adjacent sections of the transmission line.

In the operation of the rotatable joint, the spring member 2| assures positive contact between the rotatable portions of the inner conductor and the rings l2, I3 assure good electrical conduction between the adjacent sections Of the outer conductors. To assure continuity of the impedance characteristic throughout the structure, the ratio of the diameter of spherical member IE to the diameter of the spherical member 6 is made equal to the ratio of the diameter of the inner conductor 3 to the diameter of the outer conductor I. The same ratio exists between the diameters of hemispherical members I! and the parts 1 and 8. Such a construction provides uniform impedance characteristic throughout the transmission line and provides a rotatable joint which permits considerable rotation of the sections of the coaxial transmission line over a range of about degrees without introducing any electrical discontinuities in the system.

While I have shown a particular embodiment of my invention, it will of course be understood that I do not wish to be limited thereto since various modifications may be made, and I contemplate by The "resilient member or the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A rotatable joint of the universal type for connecting adjacent sections of a coaxial transmission line having a tubular outer conductor and a centrally disposed inner conductor comprising overlapping spherical parts attached to the outer conductors of said sections, the inner conductor of one of said sections having a spherical end member attached thereto, a hemispherical member movably contacting said end member, the ratio of the inner diameter of the inner of said overlapping parts to the outer diameter of said end member being equal to the ratio of the inner diameter of said tubular conductor to the outer diameter of said inner conductor, and means including a resilient member conductively connecting said hemispherical member to the inner conductor of the other of said sections.

2. A rotatable joint of the universal type for connecting adjacent sections of a coaxial transmission line having a tubular outer conductor and a centrally disposed inner conductor comprising overlapping spherical parts attached to the outer conductors of said sections, said parts being provided with contact rings for maintaining continuous conduction therebetween, the inner conductor of one of said sections having a spherical end member attached thereto, a hemispherical member movably contacting said end member, the ratio of the inner diameter of the inner of said overlapping parts to the outer diameter of said end member being equal to the ratio of the inner diameter of said tubular conductor to the outer diameter of said inner conductor, and means including a resilient member conductively connecting said hemispherical member to the inner conductor of the other of said sections.

3. A rotatable joint of the universal type for connecting adjacent sections of a'gas-filled coaxial transmission line having a tubular outer conductor and a centrally disposed inner conductor comprising overlapping spherical parts attached to the outer conductors of said sections, the outer of said parts being provided with a plurality of rings contacting the outer surface of the inner of said parts for maintaining continuous conduction between said sections, a gas-sealing means confined between said parts and said rings, the inner conductor of one of said sections having a spherical end member attached thereto, a hemispherical member movably contacting said end member, and means including a resilient member conductively connecting said hemispherical member to the inner conductor of the other of said sections, the ratio of the inner diameters of the outer and inner overlapping parts respectively to the outer diameters of said hemispherical and spherical members being equal to the ratio of the inner diameter of said outer conductor to the outer diameter of said inner conductor.

CHARLES L. ROUAULT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 284,805 Brewtnall Sept. 11, 1883 406,561 Buchanan July 9, 1889 575,615 Osyor Jan. 19, 1897 1,563,161 Christenson Nov. 24, 1925 1,870,959 Morrison Aug. 9, 1932 1,937,652 Green Dec. 5, 1933 2,179,693 Goldstein Nov. 14, 1939 2,332,529 Reppert Oct. 26, 1943 2,369,849 Phillips Feb. 20, 1945 FOREIGN PATENTS Number Country Date 368,162 France Sept. 27, 1906 

